What is the vertex of y=-(x-4)(x+4)?

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Answer 1 · 2015-12-12T04:46:51

Vertex: #(0,16)#

You are given the equation in a factor form. By setting both factors to zero you know the two roots.
#x-4=0#

#x=4#

#x+4=0#

#x=-4#

The vertex is always exactly in between those two points so you can find where x is

#x=(-4+4)/2#

#x=0#
You can see that if you graph the equation
graph{-(x-4)(x+4) [-57, 57, -28.5, 28.5]}

Now that you have x, just plug that into the equation and solve for y

#y=-(0-4)(0+4)#

#y=-(-4)(4)#

#y=-(-16)#

#y=16#

So the vertex is #(0,16)#